The present invention relates generally to scanning devices and, more particularly, to CCD image scanners.
The speed at which a scanning device can be operated is limited by several factors. One of the more important of these factors is the rate at which image data can be clocked out of the scanning device""s image sensor. In a typical scanning application, a linear image sensor is moved horizontally across a sheet of paper. As the image sensor is moved, the optically sensitive elements of the image sensor are exposed to successive areas of the page, and the signals generated within the optically sensitive elements by exposure to these areas is successively transferred out of the optically sensitive elements into associated processing electronics. In such typical applications, the speed at which a page can be scanned is limited among other things by the speed at which exposure and signal transfer can be effected.
In the competitive market of optical scanning devices, a device capable of a faster scan of an object such as a page of paper would provide an advantage. Thus, there is a need for a device having the ability to optically scan an object faster than is presently available.
An apparatus is disclosed for increasing the speed at which an object can be optically scanned. Optical signals from different small areas of an object are focused respectively onto different optical sensor arrays. Image data signals from these optical sensor arrays are interlaced in a detection circuit to form a composite image of the object, which could be for example a sheet of paper. By exposing one of the small areas during the time that the optical signal from exposure of another small area is being clocked out and by exposing the other area during the time that the optical signal from exposure of the first small area is being clocked out, the object can be scanned at a faster rate. Specialized image sensors do not need to be developed. Commercially available image sensors can be used. In particular, increased scan speed could result from placing two relatively inexpensive, commercially available Charge Coupled Devices (CCD""s) or Complementary Metal-Oxide-Semiconductor (CMOS) image sensors parallel to each other and alternatively exposing near-by areas of the object.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.